docs: def _simple_clause_to_query(clause):
          """
          Convert a clause from the Sacred Web API format to the MongoDB format.
  
          :param clause: A clause to be converted. It must have "field",
          "operator" and "value" fields.
          :return: A MongoDB clause.
          """
          # It's a regular clause
          mongo_clause = {}
          value = clause["value"]
          if clause["field"] == "status" and clause["value"] in ["DEAD",
                                                                 "RUNNING"]:
              return MongoRunDAO. \
                  _status_filter_to_query(clause)
          if clause["operator"] == "==":
              mongo_clause[clause["field"]] = value
          elif clause["operator"] == ">":
              mongo_clause[clause["field"]] = {"$gt": value}
          elif clause["operator"] == ">=":
              mongo_clause[clause["field"]] = {"$gte": value}
          elif clause["operator"] == "<":
              mongo_clause[clause["field"]] = {"$lt": value}
          elif clause["operator"] == "<=":
              mongo_clause[clause["field"]] = {"$lte": value}
          elif clause["operator"] == "!=":
              mongo_clause[clause["field"]] = {"$ne": value}
          elif clause["operator"] == "regex":
              mongo_clause[clause["field"]] = {"$regex": value}
          return mongo_clause